Process of compressing metal ingots.



PATENTED MAY 23, 1905.

R. W. HUNT. PROCESS OF GOMPRESSING METAL INGUTS.

kg MEEV APPLICATION FILED JUNE 22, 1903.

N: 9 mm; W zz/30%;

UNITED STATES Patented May 23, 1905.

ROBERT W. HUNT, OF CHICAGO, ILLINOIS.

PROCESS OF COMPRESSING METAL INGOTS.

SPECIFICATION forming part of Letters Patent N0. 790,435, dated May 23,1905.

Application filed J'une 22, 1903- Serial No. 162,605.

To all whom it may concern.-

Be it known that I, ROBERT W. HUNT, of the city of Chicago, county ofCook, and State of Illinois, have invented a certain new, use" ful, andImproved Process of Compressing Metal Ingots, of which the following isa specification.- Y

My invention relates to the art of compressing or condensing metalingots, and-has special reference to a novel process of compress inglarge steel ingots, such as are used in the manufacture of armor-plates,ordnance, ships I than the processes of compression that shafts, and thelike, for which the best of steel is required.

The object of my invention is to improve the art ofcasting andperfecting large steel ingots; and the particular object of my inventionis to provide a simple and adequate process of compressing steel ingotswhich may be conducted with less machinery and at less cost are now inuse.

My invention resides generally in .a process of compressing andperfecting steel ingots that consists in inclosing a mass of moltensteel within a closed mold, then allowing the crusts of the ingot toform, then driving a metal bar into the molten mass, and therebysubjecting the same to internal pressure and supplying the deficiencycaused. by the shrinkage of the molten metal within the ingot-crusts.

Specifically defined, my novel process consists of the following steps,to wit: pouring the molten steel into a suitable mold, then closing thetop of the mold and exerting slight pressure upon the molten contentsthereof and permitting the crusts of theingot to form, and thenthrusting a bar or mass of suitable metal through the crust of the ingotinto the molten interior thereof, thus subjecting the molten contents ofthe ingot to internal pressure and filling said ingot; and, further, myinvention consists in introducing additional masses of metal in timewith and in proportion to the shrinkage of the central portion of theingot.

.M'y invention will be more readily understood by reference to theaccompanying drawings, forming a part of this specification, and inwhich- Figure 1 illustrates the pouring of the informs.

pipe of the ingot.

the filler or pressure-bar having been placed upon the mold. Fig. 3 is asimilar view showing the first step of driving the pressure-bar,

and Fig. 4 illustrates the further introduction of the pressure-bar.

Heretofore the compression of ingots has been accomplished by theexertion of external pressure or force upon-the ingot.v I accomplishequivalent and better results by internal pressure. Whenmoltensteel ispoured into an ingot-mold, those outer portions of the metal which arein contact with the bottom and the side walls of the mold quicklysolidify. This is also trueof the top of the ingot, which is exposed tothe air and upon which a thick crust In this way the ingot is cast andtakes permanent form while its center is still molten. The molten centercools slowly and as it becomes plastic contracts within the inclosingwalls or crusts, which latter when once formed suffer little shrinkage.The contraction or shrinkage of the metal within the walls of the ingotfrequently causes the appearance of a large cavity or pipe in thecentral upper portion of the ingot, and beneath the upper orust thereof.Isolated blow holes are also likely to appear in other parts of theingot. Commercial steel is rarely pure, the same containing metalloidswhich part with their heat less readily than the steel proper, andtherefore remain liquid for alonger time. Consequently the metalloidsare finally excluded from the mass and segregated upon the surfaces ofthe different cavities and the central Their presence upon thesesurfaces prevents the welding thereof when the ingot after beingreheated is rolled, hammered, or pressed, and said pipe or cavity istherefore only elongated, always constituting a flaw in any article madefrom the ingot. To avoid such flaws, ithas been the practice to cut offthe tops of all ingots used in the manufacture of such articles asarmor-plate. The loss entailed is great, and compression has beenresorted to to avoid the necessity of cutting ofi the tops of theingots. Furthermore, it is conceded that the gases which are occluded inmolten steel and which develop therein after the steel is poured intothe mold l which is placed over the mold 3 and from have much to do withthe formation of blowholes and the pipe in the ingot. These gases tendto accumulate in the ingot mass so long as any part thereof remainsmolten and occupy the space that is left within the ingot- Walls byinternal shrinkage. Heretofore it appears to have been accepted that theonly way to obviate the formation of the pipe and other cavities was tosubject the ingot as a whole to actual compression while cooling,thereby to so far reduce its bulk as to compensate for the internalshrinkage of the ingot and the space that would be occupied by the gasesunder normal conditions. The accomplishment of compression by externalmeans requires the expenditure of great force by reason of the fact thatthe walls or crusts 0f the ingot, which from the beginning are quitesolid, must be actually compressed or broken down before the interior iseffected. The actual reduction of size is slight. My conception is thatbetter results may be accomplished by the introduction of new metal intothe molten center of the ingot to subject the same to expulsive pressureor force that will tend to fill the deficient ingot as contrasted withthe usual compression of the crusts upon the molten and shrinkingcenter.

My invention is based upon the fact that a closed vessel which is filledwith liquid cannot be added to or penetrated by a solid. without greatlyincreasing the pressure within the vessel, and obviously if an ingotthat has partially cooled is pierced and entered by a solid body anycavity which may have formed within the ingot will be filled and more orless pressure will be exerted within the ingotcrust, according to thesize of the mass which is driven into the same. By confining the ingotwithin a heavy mold its Walls may be made to withstand such internalpressure, and I find that heavy internal pressure operates not only todisplace the molten metal within said walls, but also actually defiatesor collapses the globules or bubbles of gas that may have begun to formwithin the molten or plastic metal. Such cavities may thus be reduced insize and retained in their initial 10- cations to such an extent thatthe mass as a whole may be properly termed solid, the blow-holes beingso small that they do not affect the strength of the ingot or thearticle made therefrom. I prefer in carrying out my process to employ asteel bar which after being driven through the crust of the ingot willweld or melt in the top thereof and become a part of the ingot. This maybe of better quality than the ingot metal, in which case it will tend todilute the impurities in the upper part of the ingot.

In the drawings I have illustrated apparatus of simple form andstructure, but sufiicient for the performance of my process.

In said drawings, 2 represents a steel ladle which the mold is filled.The mold rests on a stool 4 and is provided with a bottom 6. Inconnection with the bottom 6 I preferably employ a hydraulic cylinder 5and piston 7 for elevating said bottom to take up the overall shrinkageof the ingot within the mold. By raising the bottom slowly the ingot maybe kept in contact with the walls of the mold throughout the time thatthe ingot is subjected to internal pressure. The mold 3 may be securedto the stool in any suitable manner, and in practice the stool and moldare preferably movable with respect to the hydraulic cylinder. The moldis provided with a cap 8, which snugly fits the top of the mold, and isplaced therein after the mold has been filled and preferably after thetop crust of the ingot A has been formed. The cap is provided with acentral opening for the filler or pressure-bar B and also contains adriving and locking head 13, which is vertically slidable therein. Thishead may be provided with ratchets 14, and its expulsion from the cap 8is prevented by pawls or dogs 15, that engage the ratchets. The cap issecured by wedges 10, arranged in the cars 11 on the mold and bearingupon the side lugs 9 of the cap. The bar B is first placed in the capand is then topped by the driving-head 13. At this time the lower end ofthe bar B will rest upon the top crust of the ingot and be in readinessto be driven through the crust. The crust A of the ingot A may bepermitted to form and thicken for several minutes before the bar isdriven, and it is desirable that said crusts shall become suificientlysolid to prevent the bursting or eruption thereof when the molten centeror interior A of the ingot receives the bar.

During the cooling of the ingot-crust considerable shrinkage takes placewithin the same, and the bar may then be driven. For this purpose Iemploy a heavy hammer 16, one or more blows from which will drive thebar B through the top crust of the ingot and force a portion thereofdownward into the molten center of the ingot. The driving of the bar Bis continued until the pressure created within the ingot becomessufiicient to counteract the blow of a hammer or the pressure of ahydraulic piston, which may be substituted therefor, whereupon theoperation of the hammer may be stopped until further shrinkage withinthe ingot makes room for more of the bar B. The driving of the bar willthen be resumed and may be continued until the molten center becomesplastic throughout. Meantime that portion of the bar which has enteredthe molten steel will be melted and incorporated with the ingot metal. Iprefer to exert pressure upon the bottom of the ingot throughout theprocess and gage said pressure to counterbalance or counteract theinternal pressure of the ingot plus the weight of the ingot, so that themold-bottom 6 will follow the ingot as it shrinks within the mold,thereby preventing the separation of the ingot from the mold and makingit unnecessary to use a filler-bar B of suificient cubical contents tocompensate for the shrinkage of the whole ingot within the mold. Inother words, I prefer to employ the bar B only to the extent ofsupplying the deficiency of metal within the ingot itself.

It is obvious that numerous modifications of my invention will readilysuggest themselves to one skilled in the art, and I therefore do notconfine the sameto the specific steps and periods herein described.

I do not herein broadly claim the process of perfecting metal ingots byadding thereto a piece of solid metal while the ingot is cooling, as aprocess thus broadly characterized is described and claimed in mycompanion application, Serial No. 158,041, entitled Process ofperfecting ingots, filed May 20, 1908; nor do I herein broadly claimaprocess that is characterized by the thrusting of a solid bar throughthe crust of an ingot while the latter is' cooling. Processes thuscharacterized are described and claimed in my companion applications,Serial No. 158,042

and Serial No. 158,043, filed May 20, 1903,

and both entitled Process of perfecting cast-steel ingots.

Having thus described my invention, I claim as new and desire to secureby Letters Patent 1. The improvement in the art of perfecting orcompressing ingots, that consists in completely inclosing a mass ofmolten metal within a strong mold and permitting all the ingot-crusts toform within the contacting Walls of the mold, and then subjecting thecontained molten mass to internal pressure by driving solid metalthrough one of the ingot-crusts into the molten interior of the ingot,substantially as described.

2. The improvement in the art of perfecting or compressing metal ingotsthat consists in pouring molten metal into a mold and then Whollyinclosing the mass of molten metal in said mold, then permitting all thecrusts of the ingot to form, and then forcibly introducing a mass oflike, solid metal into the interior of the ingot while the same is stillmolten, thereby supplying the shrinkage deficiency of metal within saidingot-crusts, substantially as described.

3. The improvement in the art of perfecting or compressing metal ingots,that consists in wholly completely inclosing a mass of molten metalwithin a tightly-closed suitable mold, and thereafter introducingan'added mass of solid metal into the central molten part of said ingotmass whilethe latter is cooling, and there dissolving the same,substantially as described.

4. The improvement in the art of perfecting or compressing metal ingots,that consists in completely inclosing a mass of molten metal within asuitable mold, filling said mold, and then gradually driving a mass ofmetal into the ingot mass, to compensate'for the deficiency caused byshrinkage within the ingot, substantially as described.

5. The improvement in the art of perfecting or compressing metal ingots,that consists in filling a tightly-closable mold with molten metal, thentightly and completely inclosing the molten metal in said mold, and thenexpanding and filling the early-formed ingotcrusts by internal pressureby forcibly introducing a mass of solid steel, substantially asdescribed.

6. The improvement in the art of perfecting or compressing metal ingots,that consists in casting an ingot, then tightly and completely inclosingthe same in its mold, then exerting external pressure upon the end ofthe ingot, then driving solid metal through the ingot-crust and therebysubjecting the ingot to internal pressure, substantially as and for thepurpose specified.

7 The improvement in the art of compressing metal ingots, that consistsin Wholly and completely inclosing a mass of molten metal in a tapermold, exerting pressure upon the large end of the cast ingot and drivinga metal bar through the small end of the ingot, retaining said bartherein, and thereafter driving said bar farther into said ingot, sub-'stantially as described.

8. The improvement in the art of compressing metal ingots, that consistsin completely inclosing a mass of'molten metal in a suitable mold, andthereafter adding successive portions of previously-manufactured metalto the molten interior of the ingot, by driving said'portions throughthe crust of the ingot at different times, substantially as described.

In testimony whereof I have hereunto set my hand, this 15th day of June,1903, at Chicago, Illinois, in the presence of two Witnesses.

ROBERT W. HUNT.

Witnesses:

J. W. BROWN, O. G. HAWLEY.

